红景天苷通过A2AR/线粒体ATP钾离子敏感通道防治低氧肺动脉高压的分子机制研究

It's very important to find effective drugs to prevent hypoxia pulmonary hypertension. Our previous in vivo study shows that Salidroside, an ingredient of Chinese medicine can reduce pulmonary hypertension induced by hypoxia, and up-regulate the expression of A2AR, but the mechanisms remains unclear. Recent researches found that A2AR gene deletion and decrease of mitochondrial apoptosis are closed related to hypoxia pulmonary hypertension. Moreover, it was reported recently that A2AR can increase apoptosis through Mitochondrial ATP-sensitive potassium channel(MitoKATP) in coronary artery. Salidroside can protect mitochondrial has also been reported by researches. So in this study, we plan to use the technique of molecular biology, immunocyto-chemistry, confocal microscopy, patch clamp technique, electric microscopy, through both in vitro and in vivo study, using A2AR knockout mouse model we have established before, block and agitate MitoKATP, elucidate the effect of salidroside on A2AR and MitoKATP in pulmonary hypertension induced by hypoxia, and study the relationship between A2AR and MitoKATP in hypoxia pulmonary hypertension. In order to find out if Salidroside could reduce hypoxia pulmonary hypertension through up-regulate A2AR, inhibiting the opening of MitoKATP, increasing pulmonary artery smooth muscle cells ( PASMCs) mitochondria dependent apoptosis, and then inhibit the proliferation of PASMCs induced by hypoxia. The study will pay the way for finding a new way to treat pulmonary hypertension and cor pulmonale, and this study will provide experiment evidence for finding an effective traditional Chinese medicine to treat hypoxia pulmonary hypertension.

寻找有效的防治低氧肺动脉高压药物是重要的研究课题。我们前期研究发现中药成分红景天苷具有抑制在体大鼠低氧肺动脉高压的作用，并可上调腺苷2A受体(A2AR)表达，但具体机制不明；此外还发现A2AR基因缺失、线粒体途径凋亡减少与低氧性肺动脉高压的形成密切相关。据报道A2AR在冠脉能通过线粒体ATP敏感钾离子通道(MitoKATP)诱导细胞凋亡；红景天苷有线粒体保护功能。故本项目拟采用课题组前期已建立的A2AR基因敲除小鼠模型，在整体动物、离体细胞水平，利用膜片钳、共聚焦显微镜和分子生物学等技术，激动及阻滞MitoKATP，观察红景天苷对肺动脉高压、肺动脉平滑肌细胞增殖/凋亡、线粒体结构和膜电位、A2AR、MitoKATP的影响，研究红景天苷是否通过上调A2AR，阻滞MitoKATP开放，促进肺动脉平滑肌凋亡，减轻肺血管结构重建，抑制肺动脉高压，以期为开发新的防治低氧肺动脉高压的中药提供实验依据。

肺动脉高压是一项预后不良的进展性疾病，目前临床上针对其治疗方法仍有限。本项目从整体动物水平和离体细胞水平进行研究，证明了红景天苷通过腺苷2A受体（Adenosine receptor 2a, A2aR）相关的线粒体依赖性凋亡途径发挥对低氧性肺动脉高压的保护作用。第一阶段研究发现红景天苷能通过上调A2aR，降低低氧诱导的肺动脉高压、右心重构及肺动脉结构重塑，能逆转低氧诱导的肺动脉超微结构的改变；并发现红景天苷可阻断低氧诱导的线粒体相关凋亡通路。在第一阶段研究的基础上，我们第二阶段研究进一步引入A2aR KO小鼠，并在线粒体ATP敏感性钾通道（Mitochondrial ATP-sensitive potassium channel, MitoKATP）水平进行干预，探究了其具体机制：低氧条件下红景天苷可上调A2aR的表达，上调的A2aR可通过阻滞低氧诱导的MitoKATP的开放来诱导线粒体途径凋亡，抑制低氧诱导的小鼠肺动脉平滑肌细胞异常增殖，促进其凋亡，从而缓解低氧诱导的肺动脉高压。本项目的研究成果为肺动脉高压的临床治疗带来新思路，为开发红景天苷对肺动脉高压的临床治疗提供实验和理论依据，为挖掘祖国医药宝库防治肺动脉高压提供了实验基础。